Flow and air-fuel mixing processes in a premixed swirl combustor were studied with large eddy simulation (LES) method.Eddy viscosity model based on SGS(subgrid scale) turbulent kinetic energy model was selected to simulate the movement of vortex core

in order to characterize the qualitative development of coherent structures;with the introduction of unmixedness probability density function

the influences of inlet boundary conditions on eddy break-up and mixing were studied

especially the inlet velocity boundary condition;the correlation between velocity components and fuel mass fraction fluctuation shows the different velocity fluctuation factors for the mixing process.These conclusions provide useful information for further studying of premixed swirl combustor instability and pollutant emissions.